The goal of this project is to synthesize and test certain small organic phosphate compounds as potential affinity labels for glycolytic enzymes, especially those enzymes which have C-3 phosphorylated substrates such as 2-PGA, 3-PGA or PEP. We are studying 3 different kinds of compounds; (a) 2,3 epoxy propanol 1-phosphate is a reagent which esterifies a carboxyl group in the active site of triose phosphate isomerase and of enolase; we are locating the site of reaction in enolase; (b) acyl azide derivatives of 3-PGA, 2,3-DPGA and PEP are to be used as potential acylating reagents for several glycolytic enzymes and hemoglobin; (c) N-bromoacetyl derivatives of serine phosphate and isoserine phosphate are potential alkylating reagents for use particularly with phosphoglycerate mutase. BIBLIOGRAPHIC REFERENCE: "Inhibition of Glycolytic Enzymes by 2-Phosphotartrate"; Marian K. Thomas and Thomas G. Spring; accepted for publication in Biochem. J., 153 (1976).